Update provider API docs #150074

yaahc · 2025-12-16T21:46:10Z

Adds guidance on a specific provider API implementation anti pattern that implementers of the error trait should avoid.

rustbot · 2025-12-16T21:46:15Z

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library/core/src/error.rs

yaahc · 2025-12-16T21:47:40Z

library/core/src/error.rs

    /// }
    /// ```
+    ///
+    /// # Implementation Conventions


I put this at the bottom of the existing doc comment but I wasn't sure if I should feature this more prominently, the only issue is I felt like it might be confusing to provide an example of what not to do before an example of how to use it properly, but the pre-existing example is quite long so I also worry that readers will entirely miss the new section.

rustbot · 2025-12-18T23:00:45Z

This PR was rebased onto a different main commit. Here's a range-diff highlighting what actually changed.

Rebasing is a normal part of keeping PRs up to date, so no action is needed—this note is just to help reviewers.

library/core/src/error.rs

Mark-Simulacrum

r=me either way depending on how you feel about it

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Mark-Simulacrum · 2025-12-28T15:13:14Z

library/core/src/error.rs

+    /// unintended duplication of information in error reports or require heuristics to deduplicate.
+    ///
+    /// In other words, the following implementation pattern for `provide` is discouraged and should
+    /// not be used for [`Error`] types exposed in public APIs to third parties.


What is the use case for internal errors?

It seems like we could just say "don't do this", it seems clear that in fully private code people can always do whatever they want?

rustbot assigned Mark-Simulacrum Dec 16, 2025

rustbot added S-waiting-on-review Status: Awaiting review from the assignee but also interested parties. T-libs Relevant to the library team, which will review and decide on the PR/issue. labels Dec 16, 2025

yaahc commented Dec 16, 2025

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yaahc commented Dec 16, 2025

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yaahc mentioned this pull request Dec 16, 2025

Tracking Issue for error_generic_member_access #99301

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yaahc force-pushed the provider-doc-update branch 2 times, most recently from c2fcd93 to 39760d5 Compare December 16, 2025 22:02